The present invention relates to a method and an apparatus for extracting a representative sample of water, oil and sediment from a container and, in particular, a container containing fluids produced by an oil well.
Most producing oil wells produce water and sediment along with oil. The percentage of water and sediment tends to increase over time as the oil well xe2x80x9cmaturesxe2x80x9d. Whether an oil well remains economically viable at a given crude oil price, depends upon the relative percentages of water, oil and sediment produced; for it costs just as much to pump water and sediment from the oil well as it does to pump oil.
Most oil wells have installed sampling systems that systematically sample fluids produced by the oil well and store them in a collection container. The sample fluids are then poured from the collection container into a sample tube which is analyzed.
It has been determined that separation of the water, oil and sediment, is preventing a representative sample from being transferred from the collection container to the sample tube. This is causing gross inaccuracies in the water, oil and sediment data.
What is required is a method and an apparatus for extracting a representative sample of water, oil and sediment from a container.
According to one aspect of the present invention there is provided an apparatus for extracting a representative sample of water, oil and sediment from a container. The apparatus includes a container closure having a tube extending therethrough, such that fluids can be extracted from any closed container through the tube when closed by the closure. The tube has a first end and a second end. The first end is open to the flow of fluids and the second end is closed.
Several radial inlet ports are positioned at spaced intervals along the tube between the closure and the second end of the tube. Fluids from the container enter the tube at several levels through different ones of the inlet ports, thereby providing a more representative sample.
According to another aspect of the present invention there is provided a method for extracting a representative sample of water, oil and sediment from a container. A first step involves providing a container having a container closure substantially as described above. A second step involves agitating the container to mix the fluids. A third step involves creating pressure within the container sufficient to cause the mixed fluids from the container to flow out of the first end of the tube. The fluids enter through the inlet ports at spaced intervals along the tube, thereby giving a more representative sample.
There are various ways that pressure can be created inside a container sufficient to cause fluids to flow out through the tube. Beneficial results have been obtained when the container is resiliently deformable. This enables pressure to be created by squeezing the container to force fluids to exit the container via the tube.
Although beneficial results may be obtained through the use of the method and apparatus, as described above, in order to obtain the most accurate results all inlet ports must contribute substantially equal amounts of fluids to the sample. It has been determined that the contribution of each of the inlet ports becomes more equal when the inlet ports have a combined flow capacity which is less than a flow capacity of the tube.
It has been determined that the above described method and apparatus is not only more accurate, it also eliminates the mess which was formerly associated with pouring fluids from collection containers into smaller sample tubes. The fluids coming out of the tube on the above described apparatus is a steady small stream which is much easier to control. The container can now be inverted after agitating and a representative sample squeezed into the sample tube.